The effects of device geometry on the negative bias temperature instability of Hf-In-Zn-O thin film transistors under light illumination

The negative bias illumination temperature stress instability of amorphous Hf-In-Zn-O thin film transistors with different dimensions was evaluated. The threshold voltage (V(th)) shift increased in devices with shorter channel lengths but showed almost no association with the channel width. This behavior was attributed to the diffusion and drift of the photogenerated holes at the channel/dielectric interface from regions near the drain to those near the source, which were due to the simultaneous presence of gate and drain biases. The V(th) near the source, which shows the largest shift and hence has the highest local value, governs the overall V(th). (C) 2011 American Institute of Physics. [doi:10.1063/1.3541783]